1. Field of the Invention
The present invention relates to a high frequency switch, and more particularly, to a high frequency switch used in a front end portion of a wireless communications apparatus.
2. Description of the Related Art
In a case in which a high frequency switch used in a front end portion of a mobile phone, or the like, is used in, for example, a global system for mobile communications (GSM) terminal, the GSM terminal outputs a large amount of power, approximately 35 dBm, and accordingly, the high frequency switch should be capable of withstanding a correspondingly large amount of power.
As the related art associated therewith, the following structure has been known: each switching unit forming a high frequency switch is configured of a plurality of series-connected field effect transistors (FETs) and voltages are evenly divided and applied to the plurality of FETs of the switching unit, whereby the withstand voltage characteristics of the high frequency switch are improved (please refer to Japanese Patent Laid-Open Publication No. 2005-515657).
However, a metal oxide semiconductor field effect transistor (MOSFET) formed on a silicon substrate has parasitic diodes provided between source and drain terminals and a body terminal. In a case of signal transmission, when power input from a switching unit of an on-port side to an antenna through a common port increases, a parasitic diode of a MOSFET adjacent to the common port, among MOSFETs configuring a switching unit of an off-port side, is conductive, whereby a phenomenon of distorting a signal waveform occurs. This phenomenon deteriorates distortion characteristics (harmonic characteristics) of a high frequency switch. However, the related art high frequency switch may not address this problem.